/*
 * Copyright (c) 2024. The BifroMQ Authors. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *    http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and limitations under the License.
 */

package com.baidu.bifromq.mqtt.handler.v5;

import java.util.HashMap;
import java.util.Map;
import java.util.Optional;

public class ReceiverTopicAliasManager {
    private final Map<String, Integer> topicToAlias = new HashMap<>();
    private final Map<Integer, String> aliasToTopic = new HashMap<>();

    public Optional<String> getTopic(int alias) {
        return Optional.ofNullable(aliasToTopic.get(alias));
    }

    public Optional<Integer> getAlias(String topic) {
        return Optional.ofNullable(topicToAlias.get(topic));
    }

    public void setAlias(String topic, int alias) {
        Integer oldAlias = topicToAlias.put(topic, alias);
        if (oldAlias != null) {
            aliasToTopic.remove(oldAlias);
        }
        String oldTopic = aliasToTopic.put(alias, topic);
        if (oldTopic != null) {
            topicToAlias.remove(oldTopic);
        }
    }
}
